The present invention relates generally to pumps and more particularly to the geometry of the inducer blades of a pump to improve performance and prevent cavitation damage.
Background Art
As is well known in the art, inducer blade design is a compromise between various considerations for performance, structural integrity and manufacturability. For example, in considering the aspects of an inducer to arrive at maximum performance, the inducer blade thickness ideally approaches zero. Unfortunately, construction in this manner is extremely difficult and severely compromises the structural integrity of the inducer. In considering the aspects of structural integrity, a large inducer blade thickness is preferable. However, construction in this manner results in an inducer with extremely poor performance. In considering the aspects which affect the ease with which an inducer may be manufactured, it is highly desirable to simplify the geometry of the inducer blade using a single angle to define the cant of the blade.
It is one object of the present invention to provide a simplified inducer blade design which may be more easily manufactured but which has a high degree of structural integrity and provides improved performance.
It is another object of the present invention to provide an inducer having a plurality of blades whose thickness does not exceed the height of a cavitation cavity.
It is a further object of the present invention to provide an inducer having a hub which is ramped according to a fifth order polynomial.
It is yet another object of the present invention to provide an inducer whose flow passage area as taken normal to the flow of fluid varies according to a fifth order polynomial.
In one form, the present invention provides an inducer having a hub and a plurality of blades with the thickness of the blades being defined such that during the operation of the inducer each of the blades is positioned underneath a cavitation vapor line so as to improve the performance of the inducer. In another form, the present invention provides an inducer with a hub that is contoured or ramped according to a fifth order polynomial to provide improved performance. In still another form, the present invention provides an inducer having a flow passage area, as taken normal to the flow of fluid, which varies according to a fifth order polynomial to provide improved performance.